BRUSSELS — Nations fishing the Atlantic Ocean and the Mediterranean Sea have started assessing how much more prized Bluefin tuna can be caught in the next few years amid signs that stocks of the iconic fish are recovering.

The 50-nation International Commission for the Conservation of Atlantic Tunas opened its year-end meeting Tuesday in Marrakech, Morocco, facing pressure from nations to allow more Bluefin to be caught after years of cuts.

Environmentalists, however, say the recovery of the Bluefin — a prized gastronomic delight in sushi bars around the globe — is still far too fragile to shift to a major increase in fishing quotas.

The quota for eastern Atlantic Bluefin currently stands at 24,000 tons a year, but many nations are seeking an increase to reach up to 36,000 tons by 2020.

Environmental groups are willing to accept a slight increase at best.

Considering how many species have been overfished to near commercial extinction in the past few decades, from cod off eastern Canada to Mediterranean Bluefin, the challenge of increasing catch quotas and still safeguarding stocks is daunting and fraught with risk.

“The international image of ICCAT is defined by how well we manage Bluefin tuna. Consequently, decisive action on Bluefin tuna at this meeting is something that should concern us all,” said ICCAT Chairman Martin Tsamenyi. “We cannot afford to be described again as an international failure and shame, as was the case previously.”

It is exactly what environmentalists fear if ICCAT moves to increase the quotas.

“While we have seen growth in the past previous years, the species is not found to be fully recovered yet,” said Paulus Tak of The Pew Charitable Trusts.

Pew and some other environmental groups are troubled by the ICCAT’s scientific findings. On the one hand, ICCAT says that “catches of 28,000 (tons) or less have a higher than 50 per cent probability of allowing a continue(d) increase in the stock.”

Yet at the same time, the scientific committee “advises that the catches be increased using a gradual stepwise approach to 36,000 tons in 2020,” a move which some believe could end the recovery and start decreasing the amount of mature fish.

But influential partners like the 28-nation European Union and Japan are eager to believe the scientific advice behind an annual catch quota of 36,000 tons. The EU said it is moving from Bluefin recovery to management of the stocks and will close off some loopholes in the system to improve efficiency.

“A gradual stepwise increase to 36,000 tons by 2020 does not undermine the success of the rebuilding plan,” the bloc said in a statement.

Japan, where the fatty, soft texture of the Bluefin is perhaps most appreciated, said more should be caught annually.

“Everyone would like to see quotas increased by even a small amount,” said Shingo Ota, Japan’s commissioner to ICCAT. “The point is how much of quota that Japan, as the major deep sea fishing nation, can get.”

Atlantic Bluefin tuna’s annual market value stands around $200 million at the dock and four times more at the final point of sale.